Necessity of interior bearing walls when employing trusses

[Muha007]

In a one-story residence featuring a slab-on-ground foundation, spanning 12.2 meters (40 feet) in width and 22.57 meters (74 feet 1/2 inch) in length, equipped with concrete foundation walls and exterior walls composed of 2x6 studs topped with brick veneer, the inquiry arises regarding the necessity of interior bearing walls when employing trusses.

I'm curious whether the use of trusses can eliminate the requirement for interior bearing walls in this design. Alternatively, would it be necessary to incorporate interior bearing walls along with a beam stretching from one end to the other?

 

[tmurray]

Is it possible? Yes.

It all depends on your building/roof design. You should discuss this with a truss manufacturer to better understand the possibilities.

 

[Inspector Gadget]

In a one-story residence featuring a slab-on-ground foundation, spanning 12.2 meters (40 feet) in width and 22.57 meters (74 feet 1/2 inch) in length, equipped with concrete foundation walls and exterior walls composed of 2x6 studs topped with brick veneer, the inquiry arises regarding the necessity of interior bearing walls when employing trusses.

I'm curious whether the use of trusses can eliminate the requirement for interior bearing walls in this design. Alternatively, would it be necessary to incorporate interior bearing walls along with a beam stretching from one end to the other?

I see you're in Ontario ....

40-foot trusses are possible with outside load-bearing walls. Check your footing widths in that case, though. (Our office uses the principle of treating a truss span like a joist span for purposes of applying 9.15.3.4 - there's a BCBC tribunal decision that supports this interpretation here: https://boabc.org/wp-content/uploads/2021/07/18-0080.pdf)

Note that if you go more than 12.2 metres truss span, you're into Part 4 for design of the entire load-bearing assemblies from footings to truss. [9.23.1.1(1)(e)]

 

[Inspector Gadget]

(Our office uses the principle of treating a truss span like a joist span for purposes of applying 9.15.3.4 - there's a BCBC tribunal decision that supports this interpretation here: https://boabc.org/wp-content/uploads/2021/07/18-0080.pdf)

I should clarify: our office treats a truss span (if it's the only load on the footings) as a joist span. We don't double-up per the BCBC ruling otherwise: we follow the process outlined in the illustrated part 9 guide.

 

[Muha007]

I see you're in Ontario ....

40-foot trusses are possible with outside load-bearing walls. Check your footing widths in that case, though. (Our office uses the principle of treating a truss span like a joist span for purposes of applying 9.15.3.4 - there's a BCBC tribunal decision that supports this interpretation here: https://boabc.org/wp-content/uploads/2021/07/18-0080.pdf)

Note that if you go more than 12.2 metres truss span, you're into Part 4 for design of the entire load-bearing assemblies from footings to truss. [9.23.1.1(1)(e)]

Thank you very much for your reply and your valuable input! I appreciate the insight,

Is it possible? Yes.

It all depends on your building/roof design. You should discuss this with a truss manufacturer to better understand the possibilities.

Thank you, I appreciate your input! It's helpful to know that the possibility depends on the specific building and roof design. I'll definitely consider discussing this further with a truss manufacturer to gain a better understanding of the options available.

 

[Muha007]

I see you're in Ontario ....

40-foot trusses are possible with outside load-bearing walls. Check your footing widths in that case, though. (Our office uses the principle of treating a truss span like a joist span for purposes of applying 9.15.3.4 - there's a BCBC tribunal decision that supports this interpretation here: https://boabc.org/wp-content/uploads/2021/07/18-0080.pdf)

Note that if you go more than 12.2 metres truss span, you're into Part 4 for design of the entire load-bearing assemblies from footings to truss. [9.23.1.1(1)(e)]

Thank you very much for your reply and your valuable input! I appreciate the insight, your contribution adds clarity and depth to my understanding of the topic. Thanks again!

 

[SCBO1]

The truss manufactures software can calculate an approved span using all the different lumber species available to the truss manufacture. Typically the truss designer with information from the client desiring a clear span starts the process. Bearing points are typically at the end points of the truss over outside walls.

In a smaller span the bottom cord of the truss could actually go over a hallway and not actually touch the walls top plates because the truss is using the end points for bearing. To keep the truss bottom cord aligned, truss clips are sometimes used over non-load bearing walls. Bearing points other than the ends should have stickers on the truss to indicate a bearing point. A truss designer could off set bearing points in a design if that works with the interior wall placements. It's possible that the truss designer could even give the client vaults, trey ceilings, attic fan openings and attic access openings.

As tmurray advised, the truss designer or engineer should be consulted.

 

[mtlogcabin]

In a simple gable roof design the trusses should have equal bearing loads on the footings. Any other roof design with hips and valley's may have girder trusses with excessive point loads that will need to be considered in the design of the wall studs and footings supporting those large bearing loads.
The truss engineer will provide those numbers to the structural engineer designing the footings and building.

 

[mark handler]

You may need interior bracing wall to resist Lateral loads, and to transfer those loads from the roof to the foundation.